1. Field of the Invention
This invention relates to a labelling device. In particular, the invention relates to a labelling device for concentrically aligning a label with a disc and, more specifically, to a device for centring and applying labels to compact discs.
2. Description of the Prior Art
Electro-optical storage devices presently include Compact Disc Read Only Memory devices (CD-ROMs) which store digital information, the information being either or both audio and visual in nature. CD-ROMs comprise a plastic or xe2x80x9cglassxe2x80x9d disc which is etched or cut such that when placed in a CD-ROM reader and spun at high speed, the etched pattern may be identified by a laser or other scanning method.
Without some form of external marking, it is virtually impossible to identify the nature or content of the information on a given CD-ROM.
Since the capability of a CD-ROM to faithfully reproduce the information contained thereon depends in large part on the ability of the disc to be placed into a sustained, steady high speed spin about its physical centre, any marking must be done carefully to minimise disturbance of the spin.
Traditional ink based marking methods in which the ink is applied directly to the disc must use an ink that will remain in place during a sustained high speed spin. Additionally, the ink must be non-deleterious to the material of the disc. Use of conventional writing instruments, such as felt tip pens, is generally unsatisfactory since the ink may particulate and become dissociated from the disc with the potential for becoming lodged in the mechanism of the disc reader. In addition, marking in this way does not present a professional appearance if the CD-ROMs are to be sold or used commercially.
Printers specially adapted for printing onto compact discs are available. However, the cost of such printers, currently ranging between 3K and 10K, is prohibitive to those who are producing CD-ROMs in low volumes only.
An alternative to using an ink marker directly on the disc is to use a label, usually a self-adhesive label, which is subsequently attached to the disc. While in theory this seems a simple task, because of the high speed at which the disc must be spun, it is essential that the label be affixed in such a way that the overall balance of the disc is not adversely affected. In particular, it is necessary that the centre of balance of the disc remains about its geometric centre. Labels which are not concentrically affixed to the discs, for example, xe2x80x9chalf-moonxe2x80x9d or semi-circular labels, have previously caused malfunctions and often rendered the discs virtually useless.
One known device for concentrically applying self-adhesive labels to compact discs comprises a first member having a cylinder closed at one end by a slightly convex exterior face with a central aperture corresponding approximately to the size of the central aperture of a label and a second member having a plunger that includes a first portion having a diameter approximating to the diameter of the aperture of the first member and a second portion having a diameter corresponding approximately to the diameter of the central aperture of the compact disc. The first and second portions together form a shoulder against which the compact disc is seated.
In use, the operator must initially position an adhesive label on the first member so that its adhesive surface is uppermost. The label aperture is then aligned with the central aperture of the end face of the cylinder. This step alone can be difficult because of the tendency of the label to stick to the operators fingers and hence move off-centre when the operator withdraws his fingers so that the compact disc can be pressed onto the label. Also, there is a tendency for the label to curl upwards when the operator is not holding the label down.
Once the label is in its desired position on the first member, the compact disc which is retained against the shoulder portion of the plunger can be pressed down onto the label. In order to achieve the desired concentric alignment between the label and the disc, it is necessary to firmly press the disc against the shoulder portion while pushing the first portion of the plunger through the aligned apertures of the first member and the label.
Since the surface of the first member against which the label and compact disc are pressed is not planar, further care has to be taken to ensure that no air bubbles are trapped between the label and the disc as such bubbles are not only unsightly but may also cause balancing problems in the CD ROM reader.
It will be appreciated that this known device therefore relies upon the skill and manual dexterity of the operator in order to achieve correct alignment of the label and compact disc. Moreover, the device is reliant upon the operator being sufficiently well-organised to keep the two components in close proximity ready for use.
Accordingly, it is an object of the present invention to provide a device which overcomes the aforementioned problems, permitting reliable alignment of the label and disc and substantially eliminating the opportunity for operator error.
The present invention therefore resides in a device for labelling a disc having a central aperture therethrough comprising:
(i) a member having a substantially flat upper surface for supporting a label;
(ii) a disc positioning member projecting above the upper surface of the support member and for projecting through the central aperture of the disc; and
(iii) carriage means adapted to lower the disc down the disc positioning member towards the upper surface in concentric alignment with the label so that the disc and label contact each other.
By means of the invention, the disc positioning member and the carriage means maintain the label and disc in concentric alignment with each other, so no reliance is made on the skill of the operator. Moreover, the invention can be conveniently embodied in an easy to manufacture, hand-held or desktop labelling device.